Winelib allows you to compile a Win32 application to an ELF binary that can be run directly on Linux (provided the winelib is installed). But, if I understand correctly, vitamin wouldn't call such an application native, as the winelib is quite a big dependency (e.g. your application will still create the ~/.wine wineprefix). However, technically it will be a correct native binary and it should be possible to debug it using Linux native debuggers.
A bigger problem can be the VCL. It uses some Borland's C++ extensions (like properties and events) that are not handled by gcc. Also, I think winelib doesn't allow linking to binary DLLs (I think only the builtin *.dll.so and Linux native *.so), so you would need also to recompile VCL into a *.dll.so and, due to the mentioned extensions, I don't think it will be possible. Thus, I don't think it will work as winelib without some kind of a rewrite of the GUI.
You can check, however, if this works under Wine. Then you can load the binary vcl.dll and your binary compiled with Borland's compiler. There is a high probability it will work. AFAIK big apps ported using Wine usually ship an *.exe and the Wine runtime.